I haven't got Ultraxion logs yet because we were attempting Heroic Morchok all through Wednesday and Thursday night. I'll get you logs on Monday night. I'll try to do a Raid Finder run as well, just to see the Tentacle procs, not as a measure of potential dps capable. I do need to replace trinkets and get more tier pieces if possible anyway.
I'm not entirely sure about Fiery Attack proccing it, but when I looked in Wowhead, it's range was listed as 100 yds, which means it's probably not a Melee Attack and hence incapable of proccing a Tentacle?
About the 4.3 Arms BiS list, The Back, Neck and Belt are VP items and therefore do not have a Heroic upgrade. The Back and the Neck from VP items should be BiS in Heroic content as well.
Also,
Runescriven Demon Collar - Item - World of Warcraft is somewhat better than the normal Demonbone Waistguard. 67 Str+50 Mastery+87 Crit(Reforged from Haste)>221 Crit.
Ring of Torn Flesh is also a Vendor Item and does not possess its Heroic Upgrade.
Breathstealer Band - Item - World of Warcraft should be its replacement.
Rest is all good. Hopefully, chardev will be able to update these items soon and we can come up with an optimal reforging solution to see how much of each stat we get. I don't trust Simcraft one bit on this.
Oh and guys, you can just go and check any log from WoL. There are several ranked Arms Warriors above me, and I think quite a few of them use Gur'thalak, at the very least.